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From:   "Huang, Ying" <ying.huang@intel.com>
To:     Wei Yang <richard.weiyang@gmail.com>
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, mgorman@techsingularity.net
Subject: Re: [PATCH 2/2] mm/vmscan: make sure wakeup_kswapd with managed zone
References: <20220327024101.10378-1-richard.weiyang@gmail.com>
        <20220327024101.10378-2-richard.weiyang@gmail.com>
        <8735j2opd9.fsf@yhuang6-desk2.ccr.corp.intel.com>
        <20220329004146.2xdswvrm2qu7f47x@master>
Date:   Tue, 29 Mar 2022 08:43:23 +0800
In-Reply-To: <20220329004146.2xdswvrm2qu7f47x@master> (Wei Yang's message of
        "Tue, 29 Mar 2022 00:41:46 +0000")
Message-ID: <875ynxh9lg.fsf@yhuang6-desk2.ccr.corp.intel.com>
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Wei Yang <richard.weiyang@gmail.com> writes:

> On Mon, Mar 28, 2022 at 09:08:34AM +0800, Huang, Ying wrote:
>>Hi, Wei,
>>
>>Wei Yang <richard.weiyang@gmail.com> writes:
>>
>>> wakeup_kswapd() only wake up kswapd when the zone is managed.
>>>
>>> For two callers of wakeup_kswapd(), they are node perspective.
>>>
>>>   * wake_all_kswapds
>>>   * numamigrate_isolate_page
>>>
>>> If we picked up a !managed zone, this is not we expected.
>>>
>>> This patch makes sure we pick up a managed zone for wakeup_kswapd().
>>>
>>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>>> ---
>>>  mm/migrate.c    | 2 +-
>>>  mm/page_alloc.c | 2 ++
>>>  2 files changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/mm/migrate.c b/mm/migrate.c
>>> index 3d60823afd2d..c4b654c0bdf0 100644
>>> --- a/mm/migrate.c
>>> +++ b/mm/migrate.c
>>> @@ -2046,7 +2046,7 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
>>>  		if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
>>>  			return 0;
>>>  		for (z = pgdat->nr_zones - 1; z >= 0; z--) {
>>> -			if (populated_zone(pgdat->node_zones + z))
>>> +			if (managed_zone(pgdat->node_zones + z))
>>
>>This looks good to me!  Thanks!  It seems that we can replace
>>populated_zone() in migrate_balanced_pgdat() too.  Right?
>>
>
> Yes, you are right. I didn't spot this.
>
> While this patch comes from the clue of wakeup_kswapd(), I am not sure it is
> nice to put it in this patch together.
>
> Which way you prefer to include this: merge the change into this one, or a
> separate one?

Either is OK for me.

Best Regards,
Huang, Ying